
a1=[]
with open("access.log","rb") as f:
    for i in f.readlines():
        if b"f=" in i  and b"215" in i:
            a1.append(i.strip())

import re
import base64

flag=""
for i in a1:
    re1=re.compile(rb"f=(.*) H")
    re2=re.search(re1,i)[1]
    #print(re2)
    b64=base64.b64decode(re2)
    #print(b64)
    re4=re.compile(rb"\)==(\d+)\);")
    try:
        re5=re.search(re4,b64)[1].decode()
        a3=int(re5,10)
        flag+=chr(a3)
        print(flag)
        #print(re5)
    except:
        continue
